1. Field of the Invention
The instant disclosure relates to a focusing device and a chart display module thereof, and more particularly to a lens focusing device and a replaceable chart display module thereof.
2. Description of Related Art
A conventional manual focusing and measuring machine generally includes a manual focusing apparatus for adjusting an optical lens to focus on an object so as to obtain clear images of the object. The manual focusing and measuring machine has advantages of lower-cost and simpler structure, but without stability and reliability. The manual focusing process needs to rely on sight, so different users may have different perceptions of the same image of the same object. As a result, different users may have to focus on the same object repeatedly in order to obtain clear images. Moreover, a sharpness degree of the clear images will directly affect the precision of the measurement of the object during the manual focusing process.
Hence, the prior art provides an image focusing system having a plurality of curve charts for indicating sharpness of images of the object during the manual focusing process, so as to improve the focusing precision of the manual focusing and measuring machine, and avoid different users having to focus the object repeatedly. However, the curve charts provided by the prior image focusing system are fixed and irreplaceable.